A control device of a vehicle power transmission device is well known that includes a transmission capable of fixing the same rotating member with engagement of a one-way clutch and with engagement of an engagement device, the transmission having a predetermined shift stage formed on condition that at least the rotating member is fixed. For example, this corresponds to a control device of an automatic transmission described in Patent Document 1. The automatic transmission described in Patent Document 1 has a first speed gear stage (1st) as the predetermined shift stage (gear stage) and, at the time of normal start, the one-way clutch is automatically engaged to form the first speed gear stage. If acceleration is turned off during the first speed gear stage formed with such engagement of the one-way clutch and a driven state is achieved in which a drive power source side is rotated in accordance with a drive wheel side, the engagement of the one-way clutch is released. Therefore, during a so-called manual mode in which a shift stage is set based on selection through manual operation of a shift selection device, an engagement device (e.g., a brake) fixing the same rotating member (e.g., a rotating member A) as that fixed by the engagement of the one-way clutch is engaged so that the first speed gear stage is formed even in the driven state (i.e., a power transmission path is coupled (connected) between the drive power source and the drive wheels even in the driven state).
In this case, before start of the vehicle, the rotating member A is not rotated and the rotating member A may be eccentric due to its own weight relative to a supporting member (e.g., an input shaft or another rotating member). Therefore, if the brake is engaged during a manual mode, the rotating member A is fixed while remaining in the eccentric state. As a result, since the eccentricity of the rotating member A widens or narrows a gap between gears engaged with each other between members related to the rotating member A and the engaged gears come into contact with each other in a biased manner, gear noise and vibration may be increased as compared to the case that the gears come into contact with each other uniformly in a substantially aligned manner. In other words, noise/vibration performance (NV performance) may deteriorate. With regard to such a problem caused by engaging the brake in an eccentric state, Patent Document 1 describes that during the manual mode, the brake is engaged after a vehicle is started by actuating the one-way clutch to achieve the first speed gear stage. In particular, when members making up the one-way clutch (e.g., sprags) push an inner race toward the center, an aligning action of the sprags is implemented and, when the aligning action of the sprags becomes stable, the engagement state of the one-way clutch is maintained and, as a result, the rotating member A fixed by the one-way clutch is also aligned. Subsequently, the brake is engaged in the aligned state. This enables suppression of increase in gear noise and vibration.